Electrically amplified controlled stringed musical instrument



y9,194 0- M. DICKERS'ON 2 207,341

ELECTRICALLY AMPLIFIED CONTROLLED STRINGED MUSICAL INSTRUMENT Filed June1, 1957 5 Sheets-Sheet 1 Frq. 1.

Frq. 2.

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18 Inventor. 16 D. J Dickerson \12 14 Hirney y 9, 1940- D. J.DICKEFEESON 07,341

ELECTRICALLY AMPLIFIED CONTROLLE" STRIIIGED MUSICAL INSTRUMENT Fi ledJune 1, 1957 s Sheets-Sheet 2 Frg. 6. 6

- ii Q Frq. 8.

D. J. Dickerson fliiorzzeys.

y 9, 1940- D. .1. DICKERSON 2,207,341

ELEGTRICALLY AMPLIFIED CONTROLLED STRINGED MUSICAL INSTRUMENT Filed June1, 1937 S Sheets-Sheet 5 Fig.1]. 163 204 1.9.5 02 1.90

178 198 F q I i I22 Ven 02- 184/ DJ. Dickerson I V A! Hiiornqys PatentedJuly 9, 1940 amcrmcmr am NTBOLLED LIFIED C STRINGED MUSICAL INSTRUMENTDelbert I. Dickerson, West Los Aigeles, CaliL,

signalof one-half Long Beach, Calit.

to Arthur McMahan,

Application June 1, 1931, Serial No. 145,800

'15 Claims. (01. 84l.16)

My invention relates to the control or the electrical amplification of.musical instruments which are held in the hands or possibly resting onthe player's knee, such as guitars and similar type of instrument incontradistinetion to large instruments oi. a piano type. In the smallerguitar type of instrument, various arrangements have been employed bywhich the electrical amplification may be controlled by the player andchanged and varied to increase or decrease the amplitude of the soundwithout materially interrupting with .the playing. However, some'oithese employ a rheostat type of control, the rheostat being built in theinstrumentbox or case and having a controlled dial. In most of suchinstruments it is difllcult for the player to operate such dial whileplaying the instrument, having either to place the hands in an awkwardposition to operate the dial and at the same time pluck the strings.

A main object and characteristic of my invention therefore resides in acontrol for the electrical amplification in which a movable devicemounted on the instrument case may be engaged by the arm or wrist andshifted to various positions while the player's hand may be plucking thestrings. Thus presuming the player is fingering the strings with theright hand, his right wrist or forearm may operate the movable controlelement.

My invention also comprehends various ways oi! changing the electriccurrent generated by the vibration of the strings to the particularamplifying unit which varies the input to a loud speaker or the like. Myinvention therefore includes a rheostat control actuated by the movabledevice on the instrument case.

standard type of rheostat with a dial for operating the same, which dialmay be set by hand and then the auxiliary arm or wrist control mayregulate the rheostat in order to change the electric current fed to theelectrical amplifier.

My invention also includes changing the relative positions of theelectro-magnet assembly in regard to the steel strings in which thepermanent magnet having the individual electro-magnets for the variousstrings may be tilted on a longitudinal axis to vary the distancebetween the strings and the poles of the individual electromagnets. Theposition of the magnet assembly may be set to have 'a limit and thechange of position varied between these limits. This operation may becontrolled by a movable, such as a pivoted, arm or wrist rest on thebody of the instrument.

Another characteristic and type of my invention is changing the relativepositions of the poles Such case may have a of the electro-magnets inreference to the steel strings of the instrument. In this case thepermanent magnet may be held stationary and the the electro-magneticassembly with its individual poles for each string in reference to thestrings. 10 Therefore the poles of the electro-magnets may be shiftedlaterally in regard to the strings and the permanent magnet.

My invention is illustrated in connection with 2 the accompanyingdrawings, in which: 16

Fig. 1 shows a plan of a guitar type of instrument showing the form 01my invention employing a rheostat or an electric resistance device orthe like controllable by dial or by a wrist or arm actuated device tovary the electric conductivity 2 or the like of an electric elementwhich may be connected to an electrically actuated amplifying device.

Fig. 2 is an enlarged partial plan similar to Fig. 1 partly broken awayto show details of the 25 rheostat or the like control.

Fig. 3- is a transverse section on the line 3& of Fig. 2 in thedirection of the arrows.

Fig. 4 is a partial longitudinal section on the line 4-4 01' Fig. 1. 30

Fig. 5 is a partial plan of a guitar type instrument showing a modifiedconstruction in which the permanent 'and electro-magnets may be tiltedon pinions to vary the distance while maintaining the alignment betweenthe poles of 35 the electro-magnets and the assembly of strings, suchsection being partly broken away to illustrate the control by a tiltingwrist or arm operated element.

Fig. 6 is a detail longitudinal section on the 40 line 66 of Fig. 5 inthe direction of the arrows.

Fig. 7 is a transverse section on the line 'l'! of Fig. 5 in thedirection of the arrows.

Fig. 8 is a detail transverse section on the line 88 of Fig. 5 in thedirection of the arrows 5 through the main pintles of the magnetassembly.

Fig. 9 is a longitudinal section on the line 99 of Fig. 8 through themagnet assembly.

Fig. 10 is a plan of part 01' a guitar assembly 50 showing a modifiedconstruction in which the assembly of electro-magnets is shiftedlaterally to vary the distance between the poles of the magnets and thestrings of the instrument.

Fig. 11 is a transverse section taken on the line 55 formed in the topand II-II of Fig. 10 in the direction of the arrows.

Fig. 12 is a longitudinal section on the line I2-I2 of Fig. 10 in thedirection of the arrows.

In the construction of Figs. 1, 2, 3 and 4, I illustrate a guitar orsimilar instrument body II which for the electrically amplifiedinstruments is generally made of a more or less solid block instead ofhaving a resonance chamber as in the ordinary type of guitar or likeinstruments. In this case at the end of the block there is a recess I2in which is located the permanent magnet I3, this having a lower pole I4and an upper pole I5. The magnet is held in place by a set screw I6threaded in the end of the block, this extending through an ornamentalcovering material II. The covering material at the top is indicated bythe numeral it. A substantial bridge I9 extends across the recess I2 andhas the strings 20 of the guitar secured thereto. It will thus be seenthat the lower pole i4 and the upper pole I5 are located below and abovethe strings. A more or less standard electro-magnet assem-- bly 25 has awinding 26 and a series of individual pole pieces 21, there being onepole for each string and positioned directly below its string asillustrated in Fig. 2 held in place by a screw 21' at each end as shownin Fig. 4. Electric leads 28 extend from the coil to a rheostat assembly36. This may be of a standard type and the interior mechanism is notillustrated. Such assembly is mounted in a cut-out sprocket Si in theblock I I. It includes a dialing disk 32 which is attached to the cover13 by screws 33 or the like. A vertical shaft 34 extends downwardlythrough the center of the dial and has a finger operating knob 35connected thereto by a set screw 36 at the top. This knob has a pointerend 31 and may be brought to engage a fixed stop 38 on the dial disk 32.A washer 33 spaces the knob from the top of the disk. A sleeve 43 isrelatively rotatable on the shaft 34, this sleeve having a washer 4ithereabove and there being a rubber friction washer 42 between washer 4iand the underside of the dial disk 32. The sleeve is connected to adrum-like housing 43, there being a radial arm 44 connected to thesleeve and a retraction spring 45 connected to this arm and to a fixedattaching device 46 on the inside of the socket 3I. This tends to holdthe drum in a fixed position. The shaft 34 extends into the drum andbetween the shaft and the drum there is a rheostat assembly which isstandard equipment and does not form part of my present invention asmany different types of rheostats of this nature may be utilized. One ofthe rheostat assemblies which I use is manufactured by the CentralLaboratory and is quite well known on the market, However, as therheostat itself forms no part of my invention I may employ a rheostat ofthe type shown in the Stimson Patent No. 1,962,919 as element 51; in theStimson Patent No. 2,078,350 as element 49 and in the .Beauchamp PatentNo. 2,089,171 as element 43.

The control for the rheostat while playing is indicated by the assemblynumeral 69. This employs a raised cover piece 6I secured to theornamental top I6 or extending thereabove, this having an opening 62. Awrist actuated lever 63 is formedofl a plate having a fulcrum or hinge64 at one side of the opening 62, this being the side remote from thestrings. A recess 65 is this has a slot 66 through which extends anoperating arm 6i attached'to the bottom of the plate 63. A stop pin 68is secured to one or both sides of a transverse deep groove 69 extendingacross the block II and joining the socket 3|. This is to accommodate anactuating link I0 secured at H to the arm 61 and at 12 to the arm 44.One or more coil springs 13 engage the block II, passing through acut-out section on the ornamental top I8 and normally tends to elevatethe outer edge 14 of the plate 63.

The manner of operating the device of Figs. 1 through 4, as abovementioned, is by the spring 45 operating through the amp, the sleeve 40and the drum or housing 43 holds this housing in one position which maybe designated as the initial position. The knob 35 may then be rotatedwhich changes the rheostat until for instance a desired volume of toneis obtained. Should the player desire to change the tone entirely by theknob 35 he may do so provided he does not operate the hinge plate 63.Where however he intends to efiect a further control by such plate, theknob 35 may be turned until a suitable amplitude of sound is developed,this being however preferably the softest or quietest tone desired. Thenwhile the player is playing the instrument with the fingers, forinstance the fingers of the right hand being used to pluck the strings,the underside of the wrist may rest lightly on the pivoted plate 63 andthe raised section 6| of the ornamental top, Then by increasing thepressure on the plate 63 this is de-' pressed, moving the arm 61 to theleft of Fig. 2 and exerting a pull on the link ill which moves the arm44 against the tension of the spring 45. On account of the frictiondeveloped-by the friction washer 42 and the washer 33 on opposite sidesof the dial disk 32 and this washer engaging the shaft 34 with friction,the shaft and hence the knob 35 are retained from movement and themovement is developed in the drum or housing I3 while the shaft and theportions of the rheostat connected thereto are held stationary. Thischanges the electrical conductivity of the rheostat assembly and hencevaries the strength of the electrical impulses which by suitable wiringconnect to a radio type of amplifier. A jack connection 80 is used forconnection to the amplifier. It will thus be seen that the rheostat maybe controlled. either by the finger knob 35 or by the hinged plate 63while the player is playing the instrument or may be controlled by both,thus changingthe amplitude of the sound from a loud speaker or the like.

In the construction illustrated in Figs. 5 through 9 inclusive, aportion of the guitar body is indicated by the numeral 803. This has anornamental cover or finished surface Gill and is provided with a deeprecess or opening IIDZ. A permanent magnet assembly I05 has two oppositeend plates IIl6 with U shaped magnet IU'I fitted therebetween. Themagnet has a lower pole E68 and an upper pole I09, the lower pole havinga flattened upper surface H0 and the upper pole having a beveled surfaceIII. The magnet assembly is journalled on pintles II2 secured in journalblocks II3. Such pintles may be screw pins engaging in perforations inthe end plates I06. The electro-magnet assembly II5 has lower and upperplates H6 and I" with a series of poles II8 extending through theseplates and extending slightly above the upper plate. Each pole is inalignment with a string I I9, there being one pole thus directly beloweach string. The electromagnetic winding I20 forms a coil around themagnet assemblies, these thus being of a usual type. The strings aresecured in any suit- CPI able manner as by a bridging piece I2! and theleads from the magnet extend to a jack receiving socket such as shown inFig. 1.

The tilting mechanism for the wrist control designated by the assemblynumeral I25 employs a wrist engaging plate I26 having a hinge with apintle pin I 21 adjacent the edge I28 which is contiguous to thestrings, the pintle being mounted in end journals I29 and I30. A coilcompression spring I3I is seated in a recess in the block I and engagesthe underside of the plate I26. The plate at one side has a downwardlyturned arm I 35 through which the pintle pin I21 extends. This arm has aforward extension I36 which has its tip end I31 engaged in a perforationI38 on the plate I06 of the magnet assembly on the side opposite theplate I26. The compression of the spring I3I is such that it normallytilts the magnet assembly downwardly, that is, depresses the outer tipI31 of the arm I35 so that normally under the tension of such spring thepoles II8 are spaced a maximum distance from the strings.

A limiting manual control designated by the numeral I40 employs a shaftI which extends through the block I00 being journaled in a perforationI42 and held in place by a riveted end I43 with a washer and preferablya pressed washer I44. This shaft has a finger operating knob I45 at thetop attached to the shaft by a set screw I46. A helical or similarshaped screw I41 is secured to the shaft HI and extends outwardlytherefrom to contact an offset bent end [48 of a rearward extension I49of the arm I35. Thus by adjusting the knob I45 andhence the screw I41,the arm I35 and the plate I26 may be tilted on the pintle I21. This maybe used to give a manual adjustment of the position of the electromagnetpoles and the permanent magnet in reference to the strings or to form alimit to the drop or spacing apart of the magnets from the strings. Whenthis is done, then any pressure by the wrist on the plate I26 operatesto tilt the electro-magnets upwardly to bringthem in closer relationshipto the strings. Manifestly this shortens the distance between the polesand the strings and thus increases the strength of the electro-magneticfield and hence of the current through the electro-magnet winding.Therefore when the instrumentalist is playing he may at will by pressingon the plate I26 vary the position of the electro-magnet poles from thestrings, thus by change of the magnetic lines of force vary the electriccurrent through the magnets and hence the current delivered to a radiotype of loud speaker, the change being manifested in the volume of soundfrom a loud speaker or the like.

In the form of my invention illustrated in Figs. 10, 11 and 12, theinstrument block I15 has an ornamental cover I16. At one end there is arecess I11 in which is fitted a U shaped permanent magnet I18. This hasits lower arm I19 clamped to the base of the recess by a clamping boltI80. The upper arm I8I of the magnet extends above the top of theinstrument. There are a series of perforations I82 through the end ofthe magnet and through such perforations extend the strings I83. Thesemay have their ends attached as indicated at I84 to the block in asuitable manner. The strings are thus positioned substantially midwaybetween the lower and upper poles of the permanent magnet.

The slidable electro-magnet assembly I90 employs a slidable strap I9Iwhich is mounted in guide bearings I92 and I93 secured to the instrumentblock. The strap has a. slight clearance above the lower pole I19 of themagnet. Mounted on this strap is the electro-magnet assembly I95. Thisassembly has a winding I96 and a series of lower permanent poles I91. Aframe I98 of non-magnetic material such as copper strap has a lower barI99 secured to the top of the electro-magnet assembly I95 from whichopposite side pieces 200 extend upwardly and there is an upper strap orbar 20I connecting the sides, this having a clearance below the upperpole I8I of the permanent magnet. A series of complementary pole pieces202 formed of magnetizable metal are secured to the cross bar 20 I, byproviding the bar with a series of perforations 203 and thecomplementary pole pieces each extend through an opening 203 and aresecured by riveting or swaging. It will thus be seen that thisconstruction leaves a space 204 between the lower poles I91 around whichis coiled the wire forming the winding I96 and the upper orcomplementary pole pieces 202, the strings being positioned betweenthese poles as illustrated particularly in Fig. 11.

' The manual control to obtain a sliding movement of the electro-magnetsand their associated pole pieces designated by the assembly numeral 2")includes a wrist or arm actuated plate 2 having a hinge connection 2 I 2with a pintle 2 I 3 to the body of the instrument. An arm 2I4 extendsdownwardly from the underside of the plate and has a pin and slotconnection 2I5 with the end 2I6 of the strap I9I, such strap having aquarter turn 2I1 so that the end is upright. A coil spring 2I8 engagesunderneath the plate 2| I and the instrument block I 15 or theornamental cover I16 thereof. Although the strap I9I can only move witha rectilinear motion transversely of the instrument and of the Wires andalthough the arm 2I4 moves in an arcuate path, the pin and slotconnection 215 accommodates the connection between the arm and thestrap.

In the manner of operation of the invention of Figs. 10, 11 and 12, whenthe poles I91 and the complementary pole pieces 202 are in directalignment, each pair with a string I83, there is the greatest magneticflux between these poles and hence in the vibration of the strings thegreatest electric current is developed in the coil of theelectro-magnet. In this position the wrist operated plate 2 is tiltedupwardly under the action of the compression spring 2I8 and by a slightdepression or tilting downwardly of this plate a transverse movement isgiven to the strap I9I and hence to the electro-magnet assembly with itspoles slightly shifting these to one side in reference to the strings.This slightly moves the poles I91 and complementary pole pieces 202 awayfrom the direct line through the strings so that the strings are nolonger in the path of the greatest magnetic flux. Therefore the electriccurrent in the electro-magnet coil is decreased. Manifestly by operatingthe plate 2 the lateral shift of the electro-magnet with its pull piecesmay be obtained and hence the intensity of the electric currentgenerated may be varied which manifests itself in the amplitude of thesound from the loud speaker operated through a radio type ofamplification. It will be seen therefore that in the construction ofFigs. 10, 11 and 12 as in Figs. through 9, due to a change in magneticfield in reference to the strings, a change or fluctuation may bedeveloped in the electro-magnets and hence a change in the amplitude ofthe sound from a loud speaker.

Various changes may be made in the details of the construction withoutdeparting from the spirit or scope of the invention as defined by theappended claims.

I claim:

1. In a stringed musical instrument in which a plurality of strings arepositioned to be plucked by the fingers of a player and in which theinstrument is provided with an electro-magnet having an individual poleadjacent each string and an electric winding for transmission ofelectric current therethrough, the combination of a movable controldevice mounted on the instrument and positioned approximate thestringsto be engaged by part of the arm, the fingers of which pluck thestrings, with means actuated by the control device to increase ordecrease the electric current through the electro-magnet whereby onamplifying such current and translating into sound, the amplitude ofthe, sound may thus be increased or decreased, the means actuated by thecontrol device including a slidable mounting for the electro-magnetwhereby the poles may be shifted laterally relative to the strings todisplace the poles oifset or in alignment with the strings.

2. In a stringed musical instrument in which an instrument body isprovided with a plurality of strings positioned to be plucked by thefingers of the player whose arm is adapted to extend over part of theinstrument body approximate the strings and in which an electro-magneticassembly with a winding for transmission of electric current ispositioned in the instrument body adjacent to the strings, thecombination of a movable control device mounted on the said body on theside of the assembly of strings over which the player's arm is adaptedto contact and move, a movable member actuated by the c: ntrol deviceand having means to increase or decrease the electric current throughthe electro-magnet whereby on amplifying such current and translatinginto sound the amplitude of the sound may be increased or decreased, themovable member including a fixed permanent magnet and an electro-magnetassembly mounted for sliding movement transverse to the assembly ofstrings, the electro-magnet assembly having a pole piece one for eachstring and an interconnection between the control device and theelectro-magnet assembly for shifting said assembly transverse to thestrings to vary the distance between each pole piece and its individualstring.

3. In a stringed musical instrument in which an instrument body isprovided with a plurality of strings positioned to be plucked by thefingers of the player whose playing arm is adapted to extend over partof the instrument body and in which an electro-magnetic assembly has apermanent magnet and a winding for transmission of electric current witha pole piece associated with each string combined with a movable controldevice mounted on the said body on the side of the assembly of stringsover which the players arm is adapted to move and a connection from thecontrol device to at least part of the electromagnetic assemblyoperative to vary the distance between the pole pieces and the stringswith which they are associated, the permanent magnet being somewhat Ushaped and having the winding with the individual pole pieces mounted onone pole of the magnet, the magnet being journaled on pivots transverseto the strings whereby the magnet with the winding and pole pieces maybe oscillated in an arc to vary the distance between each pole piece andits associated string in the same plane.

4. A musical instrument having a plurality of strings for emittingdifierent tones, an electromagnet assembly having an individual poleadjacent each string and an electric winding for transmission ofelectric current therethrougll combined with a control device positionedto be actuated by the player of the instrument, the electro-magnet andthe poles having a movable mounting in the body for sound amplitudevari-' ation, a connection from the control device to the electro-magnetassembly to vary the distance between the poles and the respectivestrings to thereby increase or decrease the electric current resultingfrom the vibration of each string during the playing of the instrumentwhereby on amplifying such current and translating into sound, theamplitude of sound may thus be increased or decreased.

5. A musical instrument as claimed in claim 4, the electro-magnetassembly being shiftable whereby when actuated by the control device thedistance from the poles to the strings is varied while maintaining eachpole and its respective string in the same plane.

6. A musical instrument as claimed in claim 4, the electro-magnetassembly having a pivotal mounting in the instrument and the connectionfrom the control device oscillating the electromagnet assembly on itspivot to thereby vary the distance of the poles from the strings whilemaintaining each pole and its respective string in the same place.

7. A musical instrument as claimed in claim 4, a part at least of theelectro-magnet assembly including the poles being slidably mounted inthe instrument and a connection from the control device to the slidingpart of the electro-magnet assembly sliding such assembly part bodilyand thereby shifting each pole laterally from the position of alignmentwith its respective string.

8. In a stringed musical instrument of the guitar type, the combinationof a control device with a lever plate fulcrumed to the instrument by apintle parallel to the top face of the instrument and also substantiallyparallel to the set of strings on one side thereof, a spring meansnormally inclining the plate relative to the top face of the instrumentwhereby by engaging the lever with the forearm, the fingers of whichpluck the strings, said plate may be rotated on its pintie anelectro-magnetic pick-up on the instrument and means connecting thelever plate and the pick up for varying the electric current foramplification and transition into sound of changing amplitude.

9. An electro-magnetic pick-up assembly for stringed musical instrumentscomprising an electro-magnet with poles each adapted for associationwith a particular string, a pivoting mounting means for attachment tothe instrument with its pintle transverse to the assembly of strings apivot to rotate the magnet and its wound pole pieces in reference to thestrings while retaining each pole piece and its associated string in thesame plane,

11. An electro-magnetic pick-up assembly for stringed musicalinstruments including a permanent magnet with electrically wound polepieces adapted for mounting on the instrument with each pole pieceassociated with a particular string and means to vary the distancesbetween each pole piece and its associated string, the magnet having afixed mounting on the instrument and the wound pole pieces being movabletransversely of the string to laterally displace each pole piece fromthe closest position to its associated string.

12. In an electro-magnetic piclr-up assembly for stringed musicalinstruments, the combination of a magnet with a set of electricallywound pole pieces adapted for mounting on the instrument with each polepiece associated with a particular string, a control device with a leverplate fulcrumed to theinstrument by a pintle parallel to the top faceofthe instrument and also substantially parallel to the set of stringsat one side thereof, a spring means normally inclining the platerelative to the top face of the instrument, the lever plate beingpositioned to be engaged by the forearm, the fingers of which pluck thestrings to rotate the plate on its pintle and a connection between thelever plate and the set of pole pieces to move at least the pole piecesto vary the distance between each pole piece and its associated string.

13. In an electro-magnetic pick-up assembly for stringed musicalinstruments, the combination of a substantially U shaped permanentmagnet, a set of electrically wound pole pieces on one pole of thepermanent magnet, means for pivotally mounting the permanent magnet onthe instrument to align each pole piece and an associated string andmeans for tilting the permanent magnet and set of pole pieces on thepivto be engaged by oted mounting to vary the spacing of each pole pieceand its associated string while maintaining each pole piece and itsassociated string in the same plane.

14. In an electro-magnetic pick-up assembly for stringed musicalinstruments, the combination of a substantially U shaped permanentmagnet, a set of electrically wound pole pieces on one pole of thepermanent magnet, means for pivotally mounting the permanent magnet onthe instrument toalign each pole piece and an associated string andmeans for tilting the permanent magnet and set of pole pieces on thepivoted mounting to vary the spacing of each pole piece and itsassociated string while maintaining each pole piece and its associatedstring in the same plane, said tilting means comprising a lever platefulcrumed to the instrument by a pintle parallel to the top face of theinstrument and. also substantially parallel to-the set of strings at oneside thereof, a spring means normally inclining the plate relative tothe top face of the instrument, the lever being positioned the forearm,the fingers of which pluck the strings to rotate the plate on its pintleand a connection between the lever plate and the permanent magnetwhereby the magnet and pole pieces may be tilted on the pivotedmounting.

15. In an electro-magnetic pick-up assembly for stringed musicalinstruments, the combination of a substantially U shaped permanentmagnet with poles, means to fixedly attach the permanent magnet to theinstrument, a frame slidably mounted between the poles of the permanentmagnet, a set of electrically wound pole pieces mounted in the frameadapted each for aligning with its associated string. the frame beingadapted for sliding transversely to the assembly of strings to changethe spacing between each pole piece and its associated string.

DHBERT J. DICKERSON.

